The present invention relates to pressure responsive clasps, and more particularly to a clasp suitable for operation with underwater acoustic surveillance systems and ASW (anti-submarine warfare) aircraft for monitoring sound sources in large underwater areas.
Prior art systems for long-term surveillance of underwater areas for the passage of surface and submarine vessels, and other sound sources of interest, generally employ a field of hydrophones laid out at known locations and the detected sounds are retransmitted to a remote land, air or sea station for further processing and analysis. The hydrophones may be suspended from a surface buoy, and the detected sounds re radio transmitted to the aircraft. Such buoys usually experience high ambient noise and self-noise resulting from waves and high water currents, and may drift away from the area of interest. In other systems, the hydrophones are moored to the bottom and connected by cable to a remote shore station or ship. The required cable link severely limits such a system to relatively small geographical areas close to shore or in shallow waters. In addition, deployment and maintenance of the cable is extremely difficult, particularly in high sea states. A more recent proposal utilizes bottom-moored hydrophones which are linked by cable to surface buoys for radio retransmitting the acoustic data. All of these systems, however, require considerable cable for operating in deep ocean and thereby add weight, volume and cost which make them unsuitable for launching in large numbers from an aircraft.